When a heart muscle grows too thick to pump efficiently

Science · Published 24 October 2026 Swipe more like this →

In short: Imagine your heart's walls becoming so dense and stiff that they struggle to move blood. This is the reality of hypertrophic cardiomyopathy, a genetic disorder where the myocardium thickens abnormally. While many live symptom-free lives, for others, this structural change can lead to serious complications.

Hypertrophic cardiomyopathy (HCM) is primarily an inherited condition caused by mutations in one or more genes. It is most commonly passed through families, with a child of an affected individual having a 50 percent chance of inheriting the condition. In the UK, approximately 1 in 500 people are living with this disorder.

The pathophysiology involves the enlargement of heart muscle cells, which causes the walls of the heart chambers to thicken and stiffen. This structural change reduces the size of the chambers, making it harder for them to hold blood and causing the walls to struggle with relaxation. The left ventricle—the heart's primary pumping chamber—is almost always affected, along with the septum, the wall separating the left and right sides. This thickening can obstruct the flow of blood through the heart. It represents a distinct pathology from dilated cardiomyopathy, where walls become thin and stretched instead.

The clinical impact varies significantly based on the extent of thickening. While many individuals remain stable throughout their lives, others experience symptoms such as chest pain, syncope (fainting), palpitations, shortness of breath, and fatigue. In some cases, symptoms may worsen over time as the muscle gradually becomes stiffer. More severe complications can include arrhythmias, endocarditis, or a leaky mitral valve. Patients may also notice swelling in their legs, feet, ankles, or abdomen. These physical signs often accompany the general feeling of extreme tiredness.

Management focuses on monitoring the condition through physical assessments and ECGs to mitigate risks. Because HCM can lead to life-threatening abnormal heart rhythms or sudden death, early diagnosis is critical for implementing treatments that manage symptoms and reduce these serious risks. Healthcare providers use basic tests like listening to lungs and checking blood pressure for initial screening. They also monitor patients with regular appointments to track any progression.

General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.

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